1. Field of the Invention
The present invention relates to control systems and, more particularly, to low DC voltage detection systems responsive to radiated body heat for operating fluid flow valves.
2. Description of the Prior Art
Single or multi user wash basins used in industrial or commercial environments provide a source of water on demand for cleansing a user's hands, face and other body parts. Water flow valve actuating mechanisms are often manually or foot operated lever type devices to permit relative ease of use. The manually operated lever type devices may become soiled or otherwise damaged due to dirt and other contamination present on a user's hands prior to washing. The foot operated lever type devices are often subjected to abuse.
To avoid the requirements for having a user physically actuate a valve in order to cause water flow at a wash basin, various sensors have been developed and incorporated with valve actuating mechanisms to sense the presence of a user at a wash basin. Actuating apparatus of this type have included devices for generating ultrasonic energy focused upon a detector; upon a change in the energy detected due to the presence of a user, a signal may be generated for actuating a water flow valve. In one water faucet device, the faucet is rotatable to permit automatic water flow actuation or require manual valve control as a function of the rotational position of the faucet. Various devices have been developed which include a light emitter with a corresponding detector. Upon interruption of the light path by a wash basin user, actuation of a water flow valve will occur. Audio responsive detectors for actuating water flow valves associated with water basins and the like have been developed. Infrared detector systems include a generator for generating a source of infrared energy and a detector responsive thereto. Upon interruption of the infrared energy by a user, circuitry is energized for actuating a water flow valve. Several devices have also been developed for sensing the radiant energy of a human body part and actuating a water flow valve upon such sensing.
A common characteristic of prior art related devices for sensing the presence of a user and actuating a water flow valve is that such systems are active systems. That is, a signal generator is provided with a corresponding receiver. A change in signal intensity sensed by the receiver related circuitry and in response to the presence of a user, is detected and serves as a triggering signal for actuating a valve. The requirement for transmission of a signal, in combination with signal detection circuitry, imposes a requirement for a relatively substantial power supply. Such power supply requirements in essence negate the use of low voltage small capacity batteries as the power supply.